1. Field
This disclosure relates to systems used in vacuum processing, such as cluster tools used for fabricating semiconductor devices.
2. Related Art
Cluster tools are well known in the semiconductor industry. Such tools can be used for fabricating, e.g., microprocessors, memory circuits, light emitting diodes (LED), flat panel display, etc. With reference to FIG. 1, in such systems the substrates are brought to the system in clean atmospheric environment and are placed in a section of the system generally referred to in the industry as front end, mini environment, or equipment front end module (EFEM), indicated as 50 in FIG. 1. The substrates then need to be transferred into a vacuum environment. This is done by using robot 70 to remove substrates from cassettes 60 and placing them in a chamber that is generally referred to as loadlock 106. The loadlock 106 is positioned between the EFEM 50 and a vacuum chamber that is generally referred to as main frame or transfer chamber 102. A robot 104 is used to remove substrates from the loadlock 106 and place the substrate in one of processing chambers 108a, 108b, 110, and 112a-112c. 
The EFEM 50 is maintained in atmospheric pressure, while the main frame 102 is maintained in vacuum. The function of the loadlock 106 is to transfer the substrates from atmospheric pressure into vacuum pressure and vice versa. The loadlock 106 has one gate valve opening to the EFEM 50 and one gate valve opening to the main frame 102. These two gate valves are never opened at the same time. When the EFEM side gate valve is opened, the loadlock 106 is maintained in atmospheric pressure and substrates can be exchanged between the EFEM and the loadlock 106. When the main frame side gate valve is opened, the loadlock 106 is maintained in vacuum pressure and substrates can be exchanged between the mainframe 102 and the loadlock 106. On the other hand, once the substrates enter the mainframe, they can be loaded onto processing chambers via gate valves openings between the mainframe and the respective processing chamber.
3. Problem to be Solved
In some cases it is desirable to perform further processing on the substrate before or after it has been processed by the standard processing chambers. For example, sometimes the substrates have a layer that should be striped after being etched in the processing chamber. Such layer may be, e.g., a photoresist or other mask material. In standard processing the substrate may be removed from the system and sent to another system to be stripped. However, it would be advantageous to perform the further processing prior to removing the substrate from the chamber.